Biological Activity of Garcinia kola on Hepatitis C

Dwyer, Madeline
(2016)
Biological Activity of Garcinia kola on Hepatitis C.
Undergraduate thesis,
under the direction of Mark Hamann from
BioMolecular Sciences,
University of Mississippi, School of Pharmacy.

Abstract

Hepatitis C is a liver disease caused by the hepatitis C virus (HCV). According to the World Health Organization, hepatitis C infections affect between 130-150 million people worldwide. It is a major cause of liver cirrhosis and liver cancer, and approximately 500,000 people die from hepatitis C infections or related complications each year. Although new treatments are 90% effective at curing chronic hepatitis C infections, they cost tens of thousands of dollars. Available treatments are incredibly cost prohibitive, especially considering that the regions most affected by hepatitis C are Africa and central and eastern Asia (“Hepatitis C”). This creates a need for the investigation of more cost-effective HCV treatments in order to better serve the populations with the highest prevalence of HCV infections.
The seeds of Garcinia kola, often referred to as bitter kola, have been used as a folk medicine in Africa for hundreds of years. The seeds have cultural significance to some Nigerian tribes, such as the Yoruba and Ibo tribes, and they are frequently used in naming and marriage ceremonies (Adebisi 2004). In traditional African medicinal practices, the seeds have been used as an aphrodisiac, a stimulant, an antidiarrheal, a treatment for throat infections, and a cough suppressant (Okoko 2009). However, there has been peer-reviewed research revealing antihepatotoxic, antibacterial, and antioxidant activity present in the constituents of the Garcinia kola seed as well (Iwu 1987; Akinpelu; Okoko).
In this study, the seeds of Garcinia kola were ground up and gravity filtered with several solvents of differing polarities. The filtrates of these gravity filtrations were then dried using rotary evaporation, fractionated using solid phase extraction with silica cartridges or column chromatography, and dried again using rotary evaporation. After being dried, the fractions were weighed and sent off for a DCT bioassay to test for biological activity against hepatitis C.
The results of the bioassay revealed one Garcinia kola fraction with significant biological activity against hepatitis C. The hexane crude extract of Garcinia kola at a concentration of 10 μg/ml exhibited an inhibitory effect on the HCV antigen and rRNA of 39.09% and 27.56%, respectively. In an attempt to purify this crude extract, column chromatography with silica cartridges was performed using a 10% gradient of hexane: ethyl acetate. These 10 new samples were then dried using rotary evaporation. Nuclear magnetic resonance (NMR) spectroscopy was then performed on the resulting fractions in an attempt to characterize the structure of the molecule containing the hepatitis C biological activity.
However, the fractionation by column chromatography with silica cartridges of the crude hexane extract failed to completely separate the Garcinia kola into its individual constituents. Therefore, there were multiple molecules being displayed in each of the NMR spectra, making the identity of any individual constituent of the hexane crude extract impossible to deduce. Due to this complication, the results of the NMR and the identity of the molecule containing hepatitis C biological activity is incomplete. HPLC would be needed to completely purify it. However, one possible candidate for the biological activity against hepatitis C seen in the bioassay is kolaviron, a mixture of three chemically similar biflavonoids: kolaflavanone, Garcinia biflavonone 1 (GB1), and Garcinia biflavonone 2 (GB2).